WO2015120993A2

WO2015120993A2 - A device for spanning an expansion joint in the floor of a building

Info

Publication number: WO2015120993A2
Application number: PCT/EP2015/025000
Authority: WO
Inventors: Seamus Devlin
Original assignee: Seamus Devlin
Priority date: 2014-01-10
Filing date: 2015-01-12
Publication date: 2015-08-20
Also published as: WO2015120993A3

Abstract

An expansion joint cover for spanning an expansion gap in the floor of a building has a pair of edge members which are fixed in use to the floor on either side respectively of the expansion gap, a bridging member which spans the expansion gap and rests at each side on the edge members, and a centering mechanism which maintains the bridging member substantially centrally positioned relative to the edge members. The bridging member and edge members have upwardly and outwardly sloped surfaces facing one another on each side of the expansion gap. The sloped surfaces are spaced apart on each side of the expansion gap during normal non-seismic movement but engage one another if the expansion gap closes beyond a certain amount during seismic movement to displace the bridging member upwardly relative to the edge members. The cover further includes a respective flap on each side of the bridging member which is hinged along the top edge of the bridging member and extends outwardly to overlap the respective edge member.

Description

A device for spanning an expansion joint in the floor of a building

Field of the Invention This invention relates to a device (herein referred to as an expansion joint cover) for spanning an expansion joint in the floor of a structure which has been built in an area subject to seismic activity.

Background to the Invention

During an earthquake and at the instant of fault rupture, seismic waves radiate in all directions from the focus. Of the four types of waves generated by fault rupture, two, called 'body waves', travel underground through rock and soil while the third and fourth called 'surface waves' are confined to the ground surface.

Longitudinal pressure waves, sometimes termed P-waves are formed and these body waves are experienced as alternating compressions and rarefactions within the earth's crust. Similarly, body waves called S-waves or shear waves, are propagated from the seismic focus and move soil particles side to side both vertically and horizontally.

However, the particle motion of surface waves is larger than that of body waves, so the surface waves tend to cause more damage to structures.

Rayleigh waves are surface waves that are generated by the interaction of P- and S- waves at the surface of the earth and are experienced as motion of a rolling nature, much like a wave on an ocean's surface.

Love waves are surface seismic waves that cause horizontal shifting of the Earth during an earthquake. Since they decay so slowly, Love waves are the most destructive outside the immediate area of the focus or epicentre of an earthquake. They are what most people feel directly during an earthquake.

Buildings are far more susceptible to horizontal rather than vertical accelerations. The snake-like action of these waves induces into the foundations of buildings horizontal accelerations that the superstructures then amplify. The waves also transmit horizontal torsion rotations into building foundations. The primary focus of seismic resistant design is to withstand the potentially destructive effects of these waves. An integral part of the seismic resistant design of buildings is the creation of gaps between building segments. These gaps are termed expansion gaps and are breaks in the physical continuity of construction effectively sub-dividing large buildings into smaller building modules. These modules can then move independently of each other during a seismic event and the expansion gaps allow for two-dimensional relative out- of-phase movements between modules. Deflections arising from earthquakes are called 'seismic movement'.

Expansion gaps also accommodate movement rising from other forces besides seismic deflections. These deflections include movement arising from drying shrinkage, wind loading, creep, settlement and expansion and contraction of building elements due to thermal gain and loss. Within this document these deflections are collectively termed 'normal movement' or 'non-seismic movement'.

Seismic movement and normal movement are experienced variously as deflections horizontal to the plane of the expansion gap, vertical differential movement across the expansion gap and shear movement in a plane lateral to the expansion gap.

Expansion gaps run need to be covered where they pass through internal and external floors and walls, internal ceilings and roofs both to accommodate the passage of people and equipment within the building and to prevent the passage or air and ingress of water and penetration of other contaminants into the building. The term used for these products is expansion joints or expansion joint covers.

Besides accommodating deflection of the structure arising from both normal movement and seismic movement, floor expansion joint covers also have to withstand loading from a variety of sources including people, plant and equipment and vehicles of differing sorts whilst at the same time providing reasonably smooth transit from such traffic through the structure's entire movement cycle. It is particularly crucial that the expansion joint cover provides reasonably smooth transit for personnel and emergency services both during and following a seismic event.

Prior Art

Expansion joint covers comprising a centralising central pan and side frames are becoming increasingly popular for use in buildings. These central pan and side frame type expansion joint covers accommodate normal movement by means of spaces left between the central pan and the side frames. When the expansion gap opens up under seismic movement the central pan spans the expansion gap. In a seismic event where the expansion gap closes beyond the normal movement capacity

accommodated by the spaces left between the central pan and the side frames, the central pan 'pops-up' from between the side frames. A typical 'pop-up pan' expansion joint cover is shown in Figures 1 to 4, wherein Figure 1(a) is a sectional side view of the joint, Figure 1(b) is a plan view of the pan-centering mechanism of the joint, Figure 2 is a sectional perspective view of the joint, Figures 3(a) and (b) are views of the joint similar to Figures 1(a) and 1(b) showing the joint under expansion, and Figures 4(a) and (b) are views of the joint similar to Figures 1(a) and 1(b) showing the joint under compression.

Referring first to Figures 1 and 2, a pair of side frames (1) are fixed to a concrete slab or other substrate (8) forming a floor of a building by bolts or screws (6) or other suitable fixing means, the side frames (1) being fixed to the substrate along substantially parallel opposite edges respectively of an expansion gap (14) in the substrate. The side frames (1), like the side frames (20) in the embodiment to follow, may be made of extruded aluminium. Each side frame (1) has an upwardly and outwardly sloped surface (9) disposed parallel to and spaced laterally away from the inner edge of the side frame. At the inner edges of the side frames (1) there are inverted C-shaped channels (16) into which knob balls (13) are inserted. These knob balls (13) form part of an angled swivel mechanism and are fixed to opposite ends of a metal centering bar (15) which extends across the expansion gap (14) obliquely to the inner edges of the side frames (1). A series of such centering bars (15) may be provided along the length of the expansion gap (14).

A central pan (2) with sloping sides (10) parallel to the inner edges of the side frames

(1) spans the expansion gap (14) and rests on the side frames (1). The pan (2), like the pan (21) in the embodiment to follow, may be made of extruded aluminium. The sides

(10) of the pan (2) slope upwardly and outwardly at an angle which approximately corresponds to the angle of the sloping surfaces (9) of the side frames (1), i.e., the surfaces 9 and 10 are approximately parallel on each side of the pan. Within the pan

(2) a variety of finishes (11) and bedding materials (12) can be installed and this serves to reduce the visible profile width of the expansion joint cover.

A bolt (7) passes through the base of the central pan (2) and through the metal centering bar (15). A spring (3) fitted over the bolt (7) is under compression between the underside of the centering bar and a washer (4) held in pace by a nut (5) which is fitted onto the end of the bolt (7). The metal bar (15) is installed obliquely to the edges of the expansion gap (14) and, being linked at its ends to the side frames (1) and connected to the centre of the pan (2), swivels about the axis of the bolt (7) to maintain the pan (2) in a centralised position over the expansion gap (14) as the expansion gap (14) opens and closes. The spring (3) has a capacity to compress more than the depth of the pan (2) thereby allowing the pan to be totally displaced from between the side frames (1).

A respective gap (18) is left on each side of the central pan (2) between the sloping surface (9) of the side frame (1) and the sloping side (10) of the pan. These gaps (18) allow horizontal sliding movement of the pan (2) relative to the side frames (1) to accommodate normal movement as described above. At the level of the floor's surface the gaps (18) are typically filled by a sealant or a rubber or plastic extruded seal

(17) . This sealant or seal (17) is designed to accommodate limited horizontal movement and to prevent the ingress of water, dirt and other debris into the gaps

(18) . Any ingress of dirt or debris into these gaps serves to limit the normal movement capacity of the expansion joint cover.

During normal movement when the expansion gap opens, the gaps (18) widen, the central pan (2) continues to rest on the side frames (1), and the seal or sealant is put under tension and stretches to accommodate the movement.

During normal movement when the expansion gap closes, the gaps (18) close, the central pan (2) continues to rest on the side frames (1) and the seal or sealant is put under compression and compresses to accommodate the movement. Under seismic movement the expansion gap (14) can open up as shown in Figure 3. During an earthquake the gaps (18) open up and the sealant or seal that is used to fill them fails. This failure of the seal or sealant is a planned maintenance item wherein the seal or sealant is replaced following the seismic event. One problem which does arise is that the widened unfilled gaps (18) act as a grating and have the potential to be a trip hazard for those evacuating the building or for emergency services entering the building. These systems would not comply with disability regulations in force in many countries around the world where for instance the US Department of Justice's ADA "Americans with Disabilities Act" and US Department of Transports "Standards for Transportation Facilities" requires that gratings located in walking surfaces shall have spaces no greater than 1/2 in (13 mm) wide in any one direction. In the instance of existing designs of 'pop-up pan' expansion joint covers, the grating widths filled by a seal or sealant often exceed the 1/2 in (13 mm) wide before the joint has opened even under normal movement. When the joint opens the grating width increases and it becomes impossible for the system to comply with disabilities legislation.

Figure 4 shows how the pop-up pan system accommodates seismic movement when the expansion gap (14) closes beyond normal limits. During a seismic event the expansion gap closes beyond the normal movement accommodated by the gaps (18) between the sloping surfaces (9) of the side frames (1) and the sloping sides (10) of the central pan (2), to the extent that the sloping sides (10) of the pan (2) come into contact with the sloping surfaces (9) of the side frames (1). Further closure of the expansion gap beyond this point results in the central pan ((2) being displaced (cammed) upwards by the surfaces (9) such that its top surface lies above the level of the floor on either side thereby allowing the expansion gap to close more fully than if the central pan remained vertically in place. In the industry this is termed a 'pop-up pan' expansion joint cover.

In the position shown in Figure 4 the central pan (2) creates a trip hazard (19) for able bodied people leaving and emergency services accessing the building. For the elderly, people with infirmities or disabilities; particularly the wheelchair bound, the position where the central pan (2) has popped up and lies above the floor's surface presents a major obstruction to such people seeking to evacuate the building. Such systems would not comply with disability regulations in force in many countries around the world where for instance the US Department of Justice's ADA "Americans with Disabilities Act" and US Department of Transports "Standards for Transportation Facilities" requires that changes in level of ground and floor surfaces are controlled wherein a change in level up to 1/4 in (6 mm) may be vertical and without edge treatment, changes in level between 1/4 in and 1/2 in (6 mm and 13 mm) shall be bevelled with a slope no greater than 1:2 (26.5°) and changes in level greater than 1/2 in (13 mm) shall be accomplished by means of a ramp where the maximum slope of a ramp in new construction shall be 1:12 and in existing buildings between 1:8 and 1: 12 depending upon the circumstances. Hence, during seismic events when the expansion gap opens wide spaces are left between the side frames of the expansion joint cover and the central pan. As they may be construed as trip hazards and do not comply with current US disability legislation, these spaces present dangers for those seeking to exit the building and for rescuers or emergency services entering the building during or following and earthquake. Similarly when the expansion gap closes the central pan is forced upwards presenting a major obstacle to people seeking to evacuate the building. Besides presenting a trip hazard to the able-bodied, this situation is particularly problematic for the elderly and for people with infirmities or disabilities. The wheelchair bound are particularly affected where escape from the building will be hampered or prove impossible. It is these problems that this invention seeks to address.

Similar problems arise in the construction of expansion joint cover described in WO 01/98599.

Summary of the Invention

According to the invention there is provided an expansion joint cover for spanning an expansion gap in the floor of a building, the cover comprising a pair of edge members which are fixed to the floor on either side respectively of the expansion gap, a bridging member which spans the expansion gap and rests at each side on the edge members, and a centering mechanism which maintains the bridging member substantially centrally positioned relative to the edge members, wherein the bridging member and edge members have upwardly and outwardly sloped surfaces facing one another on each side of the expansion gap, and wherein the sloped surfaces are spaced apart on each side of the expansion gap during normal non-seismic movement but engage one another if the expansion gap closes beyond a certain amount during seismic movement to displace the bridging member upwardly relative to the edge members, the cover further comprising a respective flap on each side of the bridging member which is hinged along the top edge of the bridging member and extends outwardly to overlap the respective edge member.

In operation, when the expansion gap closes during a seismic event and the bridging member is displaced upwardly the flaps drop and remain in contact with the floor to form a slope or ramp permitting not only the able bodied to enter or escape from the building but also improve access and escape for the elderly, people with infirmities or disabilities and particularly the wheelchair bound and serve to meet the requirements of current disabilities legislation. When the expansion gap opens during a seismic event and the sloping surfaces of the bridging member and edge members move apart the flaps are of sufficient width continue to span the gaps between the bridging member and the edge members permitting not only the able bodied to enter or escape from the building but also improve access and escape for the elderly, people with infirmities or disabilities and particularly the wheelchair bound and serve to meet the requirements of current disabilities legislation.

Brief Description of the Drawings Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figures 1 to 4, previously described, illustrate a known expansion joint cover. Figure 5 is a sectional side view of an embodiment of the invention in its normal rest position.

Figure 6(a) is a detailed sectional view of part of the embodiment.

Figure 6(a) is an enlarged sectional view of one end of the centering bar forming part of the embodiment.

Figure 7 is an enlarged sectional view of a hinged flap forming part of the embodiment.

Figure 8 is a perspective view of the embodiment of the invention in its normal rest position.

Figure 9 is a sectional side view of an embodiment of the invention in its fully open position.

Figure 10 is a perspective view of the embodiment of the invention in its normal rest position. Figure 11 is a sectional side view of the embodiment of the invention in its fully closed position.

Figure 12 is a perspective view of the embodiment of the invention in its fully closed position.

Figure 13 is a sectional side view of a second embodiment of the invention in its normal rest position.

Figure 14 is a sectional side view of the second embodiment in its fully closed position. Figure 15 is a sectional side view of the second embodiment in its fully open position.

Detailed Description of the Embodiment Referring first to Figures 5 to 8, an embodiment of a seismic expansion joint cover according to the invention comprises a pair of edge members in the form of side frames (20) which are fixed to a concrete slab or other substrate (37) forming a floor of a building by bolts, screws, adhesive or other suitable fixing means (32). The side frames (20) are fixed to the substrate along substantially parallel opposite edges respectively of an expansion gap (14) in the substrate. Each side frame (20) has an upwardly and outwardly sloped surface (28) disposed parallel to and spaced laterally away from the inner edge of the side frame.

A horizontal channel (34) extends into each side frame (20) and terminates in a semi- circular void (33) extending continuously along the length of the channel. A metal centering bar or plate (23) has semi-circular domes (35) at each end, the bar (23) extending obliquely across the expansion gap (14) into each channel (34) with each dome (35) slidably engaging a respective void (33). These metal bar(s) or plate(s) (23) - there may be more than one disposed spaced along the expansion gap (14) - form part of an angled swivel mechanism which operates in a similar manner to that of Figures 1 to 4.

A bridging member in the form of a central pan (21) with sloping sides (29) parallel to the inner edges of the side frames (20) spans the expansion gap (14) and rests on the side frames (20). The sides (29) of the pan (21) slope upwardly and outwardly at an angle which approximately corresponds to the angle of the sloping surfaces (28) of the side frames (20), i.e., the surfaces (28) and (29) are approximately parallel on each side of the pan. Within the pan (21) a variety of finishes (30) and bedding materials (31) can be installed and this serves to reduce the visible profile width of the expansion joint cover. A bolt (24) passes through the base of the central pan (21) and through the metal centering bar (23). A spring (25) fitted over the bolt (24) is under compression between the underside of the centering bar (23) and a washer (26) held in pace by a nut (27) which is fitted onto the end of the bolt (24). The metal bar (23) is installed obliquely to the edges of the expansion gap (14) and, being linked at its ends to the side frames (21) and connected to the centre of the pan (21), swivels about the axis of the bolt (24) to maintain the pan (21) in a centralised position over the expansion gap (14) as the expansion gap (14) opens and closes. The spring (25) has a capacity to compress more than the depth of the pan (21) thereby allowing the pan to be totally displaced from between the side frames (20).

A respective gap (38) is left on each side of the central pan (21) between the sloping surface (28) of the side frame (20) and the sloping side (29) of the pan. These gaps (38) allow horizontal sliding movement of the pan (21) relative to the side frames (20) to accommodate normal movement as described above.

During a seismic event where the expansion gap closes beyond the normal movement capacity accommodated by the spaces (38), the sloping sides (29) of the central pan (21) come into contact with the sloping surfaces (28) of the side frames (20). Further closure of the expansion gap beyond this point results in the central pan (21) being displaced (cammed) upwards such that it lies above the level of the floor on either side thereby allowing the expansion gap (14) to close more fully than if the central pan remained in place.

On each side of the pan (21) a respective outwardly-facing, generally C-shaped groove or recess (41) runs along the outer edge at the top of the sloping side (29); see especially Figure 7. A pair of elongated flaps or pivot plates (22) are provided, each rounded along one edge (40). Each rounded edge (40) is dimensioned to fit into a respective C-shaped groove (41), by sliding in from one end, to form a simple hinge. By this means each plate (22) is pivoted along its edge (40) to the top of a respective side (29) of the pan (21).

These plates (22) extend laterally outwardly from the pan (21) and each overlaps a substantially horizontal surface (50) of the side frame (20) on the corresponding side of the pan. During normal movement of the substrate (37) on either side of the expansion gap (14), as the gaps (38) between the pan (21) and the side frames (20) open and close, the plates (22) will overlap the surfaces (50) of the side frames (20) to a greater or lesser extent but will remain substantially horizontal across the gaps 38 and therefore substantially level with the floor on either side.

Under seismic movement the expansion gap (14) can open up as shown in Figures 9 and 10. During these events the gaps (38) open up widely and, in the systems that employ sealant or seals, these will fail creating a potential trip hazard for those evacuating the building or for emergency services entering the building. In Figures 9 and 10 however the pivot plates (22) which, before movement overlapped the side frames (20), continue to do so and fully and substantially horizontally span the opened gaps (38) and thus provide support for anyone passing over the expansion joint cover. Figures 11 and 12 show how the pop-up pan system accommodates seismic movement when the expansion gap (14) closes. In this instance the sloping sides (29) of the central pan (21) initially come into contact with the sloping surfaces (28) of the side frames (20). Further closure of the expansion gap beyond this point results in the central pan (21) being displaced upwards such that it lies above the level of the floor on either side. In systems employing seals and sealants described earlier, the displacement of the central pan above floor level creates a trip hazard for able bodied people leaving and emergency services accessing the building. For the elderly, people with infirmities or disabilities, particularly the wheelchair bound, the position where the central pan has popped up and lies above the floor's surface presents a major obstruction to such people seeking to evacuate the building. In Figures 11 and 12 however it may be seen that the hinges (40) and (41) permit each pivot plate (22) to rotate downwardly from a position where it is parallel to and level with the floor on either side to a position (shown in dashed lines in Figure 7) where it is angled downwardly and outwardly from the edge of the pan (21) so that its free edge (52) meets the horizontal floor on either side of the pan (21). This forms a slope on either side of the central pan, such slope permitting not only the able bodied to enter or escape from the building but also improve access and escape for the elderly, people with infirmities or disabilities and particularly the wheelchair bound. A second embodiment of the invention is shown in Figures 13 to 15, wherein the same reference numerals have been used for parts the same or equivalent to those in Figures 5 to 12. The finish/bedding materials 30/31 are omitted from Figures 14 and 15. Functionally, the second embodiment operates the same as the first embodiment. The main difference is that the angles of the various sloped surfaces are more gentle than the first embodiment so that the angle assumed by the flaps 22 over the normal operating range of the device is less than that for the first embodiment. By normal operating range we mean that range of movement of the device which does not result in damage or destruction to the device or failure to perform its proper function. For example, if the width of the gap 14 exceeds some maximum - in this embodiment when the metal centering bar 15 extends across the expansion gap 14 normal to the opposite parallel edges 21 of the substrate 37 - the bar 15 will be torn out of proper engagement with its channel 34, while if the width of the gap 14 falls below some minimum the device will be crushed.

Figure 13 is a sectional side view of the second embodiment of the invention in its normal rest position. This figure is equivalent to Figure 5. In this embodiment the gap 14 is 200mm wide in the rest position. As in the case of the first embodiment the flaps 22 are substantially horizontal and overlap and slidably rest on the horizontal surfaces 50 of the edge members.

Figure 14, which is equivalent to Figure 11, is a sectional side view of the second embodiment in its fully closed position, which defines one end point of the normal operating range of the device. Here the gap 14 has closed to 100mm. In the fully closed position of the device the flaps have rotated downwardly so that their free edges rest on the horizontal floor 53 on either side of the pan 21, so that the flaps 22 form ramps inclined downwardly from opposite sides of the bridging member 21.

Figure 15 is a sectional side view of the second embodiment in its fully open position, which defines the other end point of the normal operating range of the device. Here the gap 14 has opened to 300mm. In the fully open position of the device the flaps 22 have come off the horizontal surfaces 50 and have rotated downwardly so that their free edges rest on the inclined surfaces 28 of the side frames 20, so that the flaps 22 form ramps inclined downwardly from opposite sides of the bridging member 21.

In this second embodiment the geometrical shapes of the various parts are selected so that the angle to the horizontal assumed by the flaps 22 over the normal operating range of the device is preferably less than 45 degrees, preferably less than 30 degrees preferably less than 20 degrees, and most preferably maintained below a maximum angle of about 15 degrees.

It is particularly preferred that the height to base length ratio of the right-angled triangle formed by the flap with the horizontal and vertical has a maximum value of 1:2 (0.5), i.e. the angle in the normal operating range of the device never exceeds about 26.5 degrees.

The invention is not limited to the embodiments described herein which may be modified or varied without departing from the scope of the invention.

Claims

1. An expansion joint cover for spanning an expansion gap in the floor of a building, the expansion joint cover comprising a pair of edge members which are fixed in use to the floor on either side respectively of the expansion gap, a bridging member which spans the expansion gap and rests at each side on the edge members, and a centering mechanism which maintains the bridging member substantially centrally positioned relative to the edge members, wherein the bridging member and edge members have upwardly and outwardly sloped surfaces facing one another on each side of the expansion gap, and wherein the sloped surfaces are spaced apart on each side of the expansion gap during normal non-seismic movement but engage one another if the expansion gap closes beyond a certain amount during seismic movement to displace the bridging member upwardly relative to the edge members, the cover further comprising a respective flap on each side of the bridging member which is hinged along the top edge of the bridging member and extends outwardly to overlap the respective edge member.

2. An expansion joint cover as claimed in claim 1, wherein when the expansion gap closes to displace the bridging member sufficiently upwardly the flaps rotate downwardly to maintain contact with the floor and thereby form a ramp on either side of the bridging member.

3. An expansion joint cover as claimed in claim 1 or 2, wherein when the expansion gap opens beyond a certain point the flaps rotate downwardly to maintain contact with the sloped surface of a respective edge member and thereby form a ramp on either side of the bridging member.

4. An expansion joint cover as claimed in claim 1, 2 or 3, wherein the angle to the horizontal assumed by the flaps over the normal operating range of the device is preferably less than 45 degrees, preferably less than 30 degrees preferably less than 20 degrees, and most preferably maintained below a maximum angle of about 15 degrees.

5. An expansion joint as claimed in claim 1, 2 or 3, wherein the height to base length ratio of the right-angled triangle formed by the flap with the horizontal and vertical has a maximum value of 0.5, i.e. the angle in the normal operating range of the device never exceeds about 26.5 degrees.